(…) Western leaders and Western thinkers (…) have argued for the moral imperative of intervention in various forms to prevent or stop atrocities. The ex-colonial countries of the developing world, meanwhile, have invoked the sanctity of state sovereignty. The universal adoption in 2005 of the principle of "the responsibility to protect" has blunted that divide somewhat by shifting the emphasis from the right of outsiders to intervene to the obligation of all states to prevent atrocities. But the debates over action in Burma, Sudan, Zimbabwe, and elsewhere were dominated by the same threadbare claims of sovereignty. Effective action was impossible so long as the neighbors insisted on protecting the abusive tyrant. (…)

Of course, the fact that Libya's neighbors are calling for a no-fly zone doesn't, by itself, make it a good idea. After all, they're not proposing to do anything but vote on it; the actual work would most likely have to be done by the United States and NATO, which in practice means the United States, which has the air assets in the region. And Russia or China could still block Security Council authorization for further action. But in this case, the legitimacy of Arab bodies counts for much more than the council's authorization. (…) Although Qaddafi's forces have made increasingly effective use of airpower, they would still enjoy a decisive military advantage over the rebels without it. (…)

There is no point in establishing a no-fly zone unless both the West and Arab leaders are prepared to take the next step. (…) This would be an outright act of war, though one that did not put foreign boots on Libyan soil. The goal, of course, would not be to induce Qaddafi to come to the negotiating table -- a Hitler-like Götterdämmerung is much more likely -- but to damage and demoralize his forces and thus tip the scales between the government and the rebels. (…) And according to a recent New York Times report, Qaddafi has enough cash to keep paying his militias for a long time to come.

(…) And to be effective, that action would require a serious commitment of military force. So again, why do it? Because it would be the right thing, and because it would be good for the United States. It would be the right thing because U.S. and NATO force could stop a ruthless tyrant from killing his own people and bring his monstrous rule to an end. Western intervention in the Congo wouldn't have solved the problem, while military action in Darfur might well have provoked a massive backlash in the Islamic world. But Libya is a case where force could work and where it will be deployed only after non-coercive methods have proved unavailing, as the doctrine of the responsibility to protect requires. And it would redound to America's benefit because the United States would be placing its military power at the disposal of the Arab world in order to liberate Arab peoples.

Of course, absolutely everything about such a plan could go wrong. The Arab League could change its mind once the rubble began to fly; an American plane could get shot down; missiles could go awry and kill civilians; a rebel victory could throw Libya into chaos, or sharia, or back into charismatic authoritarianism. Or surgical strikes, like a no-fly zone, could prove unavailaing. What then? A full-scale intervention? (Answer: It's a moot point, because the neighbors would never approve it.) And since any of these things could happen, the dictates of prudence might argue that U.S. policymakers take a pass at the unprecedented invitation to act.

White House officials, of course, are hoping that the rebels will win on their own. So is everyone. But if the rebels keep floundering, as seems increasingly likely, President Barack Obama will have to choose either to act or to forego action. We have learned that his idealism is even more tempered by caution -- by prudence -- than we had initially thought. It's very hard to predict which way he'll go. I know which I would prefer.